1. Field of the Invention
The present invention relates to an image forming apparatus that forms an image on the basis of PDL information.
2. Description of the Related Art
A trapping method (a print method wherein boundary portions of colors are made to overlap each other), an overprint method (a print method wherein the color of an object to be drawn is made to overlap another color) and a black overprint method (a print method wherein black is made to overlap another color) are known as methods of preventing occurrence of “white gap” due to misregistration of a black character, a black line, etc. in conventional image forming apparatuses.
An electrophotographic color printer forms a print image by overlapping four colors (Y, M, C, K). If misregistration in color takes place, an unsightly white gap occurs conspicuously on a high-density region, in particular, in the case of a black character on a dark background, or black graphic. One of measures to overcome this problem is a BOP (Black Over Print) process.
In the BOP process, a background region, which overlaps a black object, is not erased, and a neighboring background pattern is made to remain under the black object. Thus, exposure of the background due to misregistration is prevented. In the BOP process, the color to be processed is limited to black. However, a white gap due to misregistration is similarly conspicuous with respect to dark gray with high density, and the appearance of print matter becomes poor (degradation in image quality).